1. Field of the Invention
The invention relates to open end yarn processing and its fabric properties.
2. Description of Prior Art
The invention relates to a method and apparatus which are suitable for processing on open end (OE) spinning systems, and is more particularly concerned with rotor spinning system and downstream processing on such systems.
The open end spinning system has achieved a major breakthrough because the twist insertion in this spinning system is no longer performed by the rotation of yarn packages and thus this system eliminates the friction problem that limits ring-spinning. As a result, OE spinning techniques have had a phenomenal growth in productivity, due to amenability to automation, and elimination of roving and winding processes. Therefore, this technique has established itself as a worthy alternative to the ring spinning system. alternative to ring spinning system.
However, OE spun yarns have not penetrated the yarn market to the extent expected because along with the positive aspects there is a growing realization that the system has sectorial applicability-viz, the techo-economic considerations have restricted rotor spinning to coarse and medium counts. These demerits made this new system less attractive than ring spinning technique, which can handle a diversity of fibers and produce a broad range of yarn counts. What is more, the OE spun machine produces a weaker yarn, usually with a 10-30% lower tenacity, as compared to ring spinning. This strength loss is related to the accentuated obliquity effect and higher proportion of noncontributing fibers existing in an OE spun yarn.
However, the biggest drawback of OE yarns is the harsh feel of the fabrics made out of such yarns. Particularly, the harsh feel limits the end use of its end fabrics. For example, knitted fabrics produced from OE spun yarns are unsuitable for using as underwear material. The harsh feel can be attributed to the structure of the yarn, and especially to that of the surface fibers. In particular, it is believed that the tight surface fibers, including wrapper fibers and undulation of the yarn surface, are assumed to be the main cause of harsh feel. Besides, the higher twist adopted in OE yarn and thus higher obliquity of fibers is another significant influential factor. Moreover, fabric produced from OE yarn suffers from a duller appearance, which is also undesirable for end use.
It is therefore an object of the present invention to provide a method and an apparatus for improving OE yarn/fabric structural properties, modifying yarn physical properties, and altering the appearance and handling properties of fabrics made out of rotor spun yarn.
It is an object of this invention to overcome or at least reduce this problem.
According to the invention there is provided a method for improving structural and physical properties of open end yarn and articles made of open end yarn, including tensile drawing the yarn between rollers driven at different velocities and directing a jet of air at the yarn between the rollers to temporarily untwist the yarn as it is drawn.
An apparatus for improving structural and physical properties of open end yarn and articles made of open end yarn, comprises at least two rollers which are separated by a drawing zone, in which the rollers are controlled to rotate at different velocities to apply tension to the open end yarn as the open end yarn passes through the drawing zone and an air jet directed at the drawing zone to temporarily untwist the yarn as it is drawn.